Calculate the formula mass of CuSO4.5H2O.
[Atomic mass of Cu = 63.5 u, S = 32 u, O = 16 u, H = 1 u]
Formula unit mass of CuSO4.5H2O:
Atomic mass of Cu + Atomic mass of S + (4× atomic mass of O) + 5 (2× atomic mass of H + atomic mass of O)
63.5 u + 32 u + 4× 16u + 5 (2 × 1 u + 16 u)
63.5 u + 32 u + 64 u + 90 u
249.5 u
Thus, the formula unit mass of CuSO4.5H2O is 249.5 u